The field of the disclosure relates generally to systems and methods for active clearance control in aviation engines and, more particularly, to a system and method for active clearance control for high pressure compressors using fan exhaust air.
Aircraft engines generate heat in high pressure compressors. High pressure compressors included disks, compressor blades, and compressor casings. Thermal expansion of disks, compressor blades, and compressor casings change the clearance between the compressor blades and the inner compressor casing. Engine inefficiencies occur when the clearance between the compressor blades and the inner compressor casing is too large, thereby facilitating decreased compressor pressure rise capability and decreased stability. Active clearance control maintains the clearance between the compressor blades and the inner compressor casing. At least some of the known methods for controlling the clearance between the compressor blades and the inner compressor casing are active thermal control and active mechanical control. For example, some known active thermal control methods use compressor bleed air and fan exhaust air to cool the inner compressor casing. Compressor bleed air and fan exhaust air are directed to the outer radial surface of the inner compressor case. The compressor bleed air and fan exhaust air cool the inner compressor casing. The active thermal control method has a slow thermal response.
In addition, some known active mechanical control methods use linkages and actuation to control the clearance between the compressor blades and the inner compressor casing. Segmented shrouds attached to a unison ring and actuators individually control the positioning of each shroud. The active mechanical control method has a quick response rate, but the additional equipment required for the active mechanical control method adds weight to the aircraft.